A problem encountered in connection with the collection and purity control of samples from pressurized liquid systems, such as hydraulic and central lubricating systems, is to obtain representative samples for verifying the particle purity of a sample in a particle counter or microscope. Frequently the sampling bleed orifice and valves have to be purged for a considerable time before the sample is representative. Also, current methods frequently cause considerable oil spillage since, in order to be representative, a sample requires up to half an hour of purging through the sampling bleed orifice. Further, during opening and closing of sampling bleed valves on the pressure side of the liquid system, the sample is contaminated by particles liberated in such valves.
DE 3 927 020 A1 discloses a rather complicated sampling device for taking samples of toxic or noxious fluids in a circulation system. The sampler includes a sampling container which may be of a pressure resistent type if the fluid is under pressure in the circulation system. The fluid may be caused to flow from the circulation system into the sampler via a bleed valve to be closed when the sampler has been filled as desired. Since the opening as well as the closing of the bleed valve will result in microscopic extraneous matter entrained in the fluid flowing into the sampler, this prior device would be entirely impracticable in verifying the purity of the liquid circulating in the system. Furthermore, a pressure resistant container would be expensive.
Also exemplary of the prior art is GB-2 222 675 A disclosing a relatively complex device for taking samples of a radioactive flowing liquid. The liquid is discharged into a sampling flask by utilizing the venturi effect, and the discharge ceases automatically when the sampling flask is removed from the flow system. However, the device cannot be used on pressurized fluids.